Genetic and phenotypic of Pseudomonas aeruginosa sensitive to meropenem antibiotics after exposure to meropenem.

Abstract

Background and objectives: Pseudomonas aeruginosa, drug-resistant, causes health infections. Resistance to the preferred therapy meropenem is a serious threat. This study aimed to analyze changes in meropenem minimum inhibitory concentration (MIC), changes in ampC, mexA, and oprD gene expression, and the correlation between MIC and ampC, mexA, and oprD gene expression after meropenem exposure.

Materials and methods: Ten isolates of P. aeruginosa from the Clinical Microbiology Department, Faculty of Medicine, Universitas Indonesia were used. After the bacteria were shown to be sensitive to meropenem phenotypically, intrinsic resistance genes were detected using PCR. After meropenem exposure on Days 5 and 12, sensitivity testing was carried out with the concentration gradient method and RNA was detected using real-time RT-PCR.

Results: All P. aeruginosa isolates that were phenotypically sensitive to meropenem had the ampC, mexA, and oprD genes. An increase in MIC, an increase in ampC and mexA gene expression, and a decrease in oprD gene expression were observed after meropenem exposure. There was a very strong and significant correlation (p ≤ 0.05) between MIC and oprD gene expression after Day 12 of meropenem exposure.

Conclusion: Although there were no significant differences in MIC and ampC, mexA, and oprD gene expression between Day 5 and Day 12, there was a very strong and significant correlation between MIC and oprD gene expression on Day 12 (p ≤ 0.05). This indicates that decreasing oprD gene expression has the potential to increase meropenem resistance in Pseudomonas aeruginosa.